Capacitive Load Driving Circuit Layout for Ink Jet Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In liquid discharging apparatuses like ink jet printers, high oscillation frequencies required for accurate ink discharge lead to noise interference, affecting discharge accuracy due to inadequate component layout in capacitive load driving circuits.
Innovation Solution
A layout configuration where the ground terminal and feedback terminal are adjacent on the same semiconductor substrate, with the power source terminal optionally nearby, and the gate driver separated from the modulation portion, reduces noise interference by stabilizing potential and separating noise sources, enabling precise voltage control of piezoelectric elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high oscillation frequency (1 MHz to MHz) is used in class-D amplifier for ink jet, then discharge accuracy is improved, but noise interference increases
Solution Approach 1:
The patent segments the IC into distinct functional regions: a first region containing the modulation portion and gate driver, and a second region containing the power source terminal, ground terminal, and feedback terminal. This spatial segmentation isolates noise-sensitive feedback circuits from noise-generating switching circuits, allowing high oscillation frequency operation while minimizing noise interference.
Solution Approach 2:
The feedback terminal is extracted and placed in a separate second region away from the modulation portion and gate driver. This extraction removes the feedback signal path from the noisy switching region, enabling high-frequency operation without degrading discharge accuracy due to noise.
2Loss of energy
If class-D amplifier is used instead of class-AB amplifier, then energy efficiency is improved, but discharge accuracy deteriorates due to noise
Solution Approach 1:
By segmenting the IC layout into noise-isolated regions, the patent enables class-D amplifier operation (which is energy-efficient) without sacrificing discharge accuracy. The segmentation protects the feedback signal from noise, maintaining waveform accuracy while benefiting from reduced energy loss compared to class-AB amplifiers.
3Object-affected harmful factors
If ground terminal and feedback terminal are separated, then noise resistance is improved, but device complexity increases
Solution Approach 1:
The patent implements segmentation by defining two distinct regions on the IC: the first region for modulation and gate driving, and the second region for feedback and grounding. This structured segmentation provides noise resistance while maintaining systematic design complexity rather than random complexity.
Solution Approach 2:
The ground terminal is placed in the second region adjacent to the feedback terminal, creating an equipotential reference area. This placement ensures that the feedback signal has a stable reference potential close to its sensing point, improving noise resistance without requiring complex external grounding arrangements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances discharge accuracy by minimizing external noise impact on feedback signals, allowing for high-frequency modulation signals (1 MHz to 8 MHz) that maintain waveform sharpness and prevent discharge defects, while maintaining power efficiency.
Implementation Method 1
a piezoelectric element which is displaced as the driving signal is applied; a cavity in which the inside is filled with liquid and the internal volume changes due to the displacement of the piezoelectric element
Data Source
AI summary
There is provided a liquid discharging apparatus including: a modulation portion which generates a modulation signal pulse-modulated from a source signal; a ground terminal which electrically connects the modulation portion to a ground potential; a transistor which generates an amplification modulation signal amplified from the modulation signal; a low pass filter which demodulates the amplification modulation signal and generates a driving signal; a feedback circuit which generates a feedback signal based on the driving signal, and sends back the feedback signal to the modulation portion via a feedback terminal; and a piezoelectric element which is displaced as the driving signal is applied, in which the modulation portion, the ground terminal, and the feedback terminal are formed on the same semiconductor substrate, and in which, in a plan view, the ground terminal and the feedback terminal are disposed being adjacent to each other.